Do you mean within your instance or outside it?

If outside, check out the collections page at kbin.social - even if you can’t navigate to it from your instance (you probably can though since it’s another kbin) it’s worth looking through some of the collections (multis).

E.g you might be interested in the multi-community feed https://kbin.social/c/PCGaming

Another thing worth doing is go to a magazine you like, click on the microblog tag to see the associated Mastodon posts, and then start looking at the people and exploring the hashtags. I have found some really good content that way.

Also, following people who post interesting stuff in one of your existing communities and seeing where else they post.